RATE AND TEMPERATURE DEPENDENT MECHANICAL PROPERTIES OF A FLEXIBLE ADHESIVE

Design stress analyses of adhesively bonded structures may be performed using Finite Element methods provided that suitable material models and mechanical properties data are available. Flexible adhesives appear to be best modelled by hyperelastic models. However, their properties are dependent on strain rate and temperature. The aim of this work is to characterise the behaviour of a typical flexible adhesive. Statistical analysis of bulk specimen tensile and single-lap joint shear tests shows that stress at failure increases with decreasing temperature and increasing strain rate. Strain-to-failure shows less significant dependence. Within the hyperelastic temperature region and at strain rates up to 10-1s-1, the statistical analyses show that temperature has a higher influence than strain rate on the material properties. There is a reasonable correlation between failure stress values in tensile and single-lap joint tests. The mechanical properties have been investigated using visco-elastic models. Rate dependence of the adhesive stress-strain response can be described using a relaxation model. Time-temperature superposition shows some promise for modelling the failure of the adhesive specimens